Tobacco smoking article

ABSTRACT

The formation of a shredded tobacco material having intimately mixed therewith a microencapsulated synthetic clove flavoring material wherein the capsules are of such a size as to create an audible crackling sound when burned and the incorporation thereof into smoking articles such as cigarettes, cigars, etc. The capsules may also contain a tobacco flavor enhancer.

United States Patent lnventor Alton Dewitt Quinn Cranford, NJ.

Appl. No 877,820

Filed Nov. 18, 1969 Patented Nov. 30, 1971 Assignee InternationalFlavors & Fragrances, Inc.

New York, N.Y.

TOBACCO SMOKING ARTICLE 4 Claims, No Drawings U.S. Cl 131/9, 13l/10.1,131/17 Int. Cl. A241) 15/04 FieldoiSearch 131/9,15, 17, 140-144, 10.1

References Cited UNITED STATES PATENTS Keaton 131/15 PrimaryExaminer-Melvin D. Rein Attorneys-Arthur L, Liberman and Ward,McElhannon,

Brooks & Fitzpatrick ABSTRACT: The formation of a shredded tobaccomaterial having intimately mixed therewith a microencapsulated syntheticclove flavoring material wherein the capsules are of such a size as tocreate an audible crackling sound when burned and the incorporationthereof into smoking articles such as cigarettes, cigars, etc. Thecapsules may also contain a tobacco flavor enhancer.

TOBACCO SMOKING ARTICLE This application is a continuation-in-part ofour copending application Ser. No. 851,058, filed Aug. 18, 1969.

THE INVENTION This invention relates to an improvement in tobaccowhereby a plurality of minute, heat rupturable capsules each containinga synthetic clove oil as an inner phase are mixed in integral contiguousrelationship with shredded tobacco. As tobacco surrounding each discretecapsule burns, the elevation in temperature is such that capsule wallsrupture, thereby releasing a discrete quantity of clove oil vapor whichbecomes entrained in smoke issuing from the burning tobacco. Thecapsules being spaced homogeneously throughout the length of the smokingarticle, the capsule walls rupture successively, or consecutively, withthe advance of the burning front of ignited tobacco. The exeunt smokeinhaled by the smoker is homogeneously aromatic. The capsules are ofsuch a size diameter) that the rupture thereof gives rise to an audiblecrackling sound; a property desirable for cigarettes, cigars, etc.marketed in certain nations in the Far East such as Indonesia.

This invention also relates to shredded tobacco and more particularly tocapsule containing shredded tobacco compositions, methods for producingthe same, and to smoking articles, such as cigarettes, cigars and thelike containing desired quantities of encapsulated synthetic clove oil.

The present invention can be practiced by admixing a capsule slurry withshredded tobacco. It has been found that although tobacco tends to burnwith acridity, the acridity is masked or nullified by the flavoring ofsmoke from the buming of said tobacco with encapsulated odoriferousclove flavors.

It has been recognized that the addition of clove oil as well as othertobacco flavor enhancers to tobacco imparts a pleasant flavor to thetobacco. In methods hitherto used, the tobacco has been treated bysoaking it in a suitable solution of natural or synthetic clove oil orthe solution has been sprayed on the tobacco. One disadvantage of suchprocesses is that the clove oils which are suitable for this use have anappreciable vapor pressure at ordinary temperatures and for that reasonthe substance more or less rapidly vaporizes and escapes. Furthermore,natural clove oils are relatively expensive. In the process of thisinvention, inexpensive synthetic clove oil may be used and whenencapsulated in microcapsules, this substance does not vaporize andescape. In addition, the microcapsules are of such a size (50500microns) that when the smoking article is burned, when in use, thecapsules rupture with an audible crackling sound. Such a property isdesirable in smoking articles marketed iq such Far Eastern nations asIndonesia. A means of overcoming the acridity of shredded tobacco byincluding synthetic clove oil containing capsules admixed therewith isto mix the capsules in slurry form with the shredded tobacco.

in addition, the subject invention provides a system for the penetrationof capsular clove oil-containing material applied to a wet fibroustobacco sheet which affords the advantages inherent in having saidcapsules disposed within the body of the sheet material and yetaccomplishes this end without concomitant intolerable loss of thecapsules to achieve it. The sheet is shredded subsequent to being coatedand dried.

In the tobacco industry, and particularly that part of the industryrelating to the manufacture of cigarettes, cigars and like smokingarticles, large quantities of tobacco are rejected annually and sold aswaste because it is either impossible or impracticable to utilize themin the manufacture of smoking articles. Obviously the loss of thesematerials is a serious matter from the point of view of themanufacturers and, therefore, it would be highly desirable if suchmaterials could be salvaged and used in the manufacture of smokingarticles. Materials now disposed of as waste are tobacco stems, dust,scrap, clippings and other portions which are unsatisfactory inconnection with the manufacture of high-grade smoking articles.

From time to time attempts have been made to form tobacco sheets orfilms which would solve the problem of satisfactorily disposing of orutilizing tobacco waste materials. Processes have been developed forforming tobacco paper utilizing well-known paper processes andtechniques in which tobacco waste, such as for example stems and scraps,has been reduced to pulp by the use of chemicals, and then according toordinary paper making techniques converted into paper. These techniquesare unsuitable for use either in connection with the present inventionin forming improved tobacco sheet material, carrying out the processestherefor, and producing novel smoking articles, such as cigarettes orcigars, because of the radical changes to which these tobacco materialsare subjected, and the loss of valuable constituents and properties ofnatural tobacco.

According to one aspect of this invention, tobacco sheet or filmmaterial may be made along lines similar to those described anddisclosed in U.S. Pat. No. 2,433,877, in which the final productcontains substantially all of the desirable properties and naturalcharacteristics of tobacco, especially insofar as aroma, taste and colorare concerned, and has the same general appearance of tobacco.

An object of this invention is to provide an aromatic content which isclosely similar to distilled clove oil to smoke from an unfilteredcigarette, or a filtered cigarette.

Another object of this invention is to prevent the premature loss ofvolatile synthetic clove oil flavoring material from smoking articlessuch as cigars, cigarettes, etc.

Another object of this invention is to coat reconstituted tobacco sheetmaterial with capsules containing a synthetic clove oil material.

Another object of this invention is to provide a synthetic clove oilflavor containing reconstituted tobacco sheet material in which theclove oil flavor is invisible and undetectable prior to smoking saidreconstituted tobacco sheet material.

Another object of this invention is to provide a mixture of shreddedtobacco and microcapsules which yield a volatilized clove oil flavorwhen the tobacco is burned, and, simultaneously rupture with an audiblecrackling sound.

Another object of this invention is to provide a novel reconstitutedtobacco sheet which has the advantage of physical protection of capsulescontaining synthetic clove oil flavoring from touch and sight. To theend that the particles (capsules) may be confined within the sheet, theyare of necessity smaller in their average diameter size than the sheetthickness and preferably are of such size, and present in such quantity,that they are protectively nested in the interstitial spaces between thetobacco fibers of the reconstituted tobacco support sheet, in additionto being adherent to the tobacco fiber, even if calendered, withoutdisturbing, from a user's viewpoint, the normal physical structure ofsuch a sheet made without them.

The instant invention encompasses mixtures of shredded tobacco andmicroscopic capsules each containing an inner phase comprising asynthetic clove oil material; and methods of forming such mixtures,including the method of forming continuous, self-supportingreconstituted tobacco films or sheets which comprises forming an aqueousslun'y of comminuted tobacco stems, forming said slurry into acontinuous thin web, and applying to said web microscopic capsules eachcontaining an inner phase comprising volatile clove oil flavors and, ifdesired, additional tobacco flavor enhancers such as those described inCanadian Pat. Nos. 805,933; 805,934; 805,459; and 805,460.

The tobacco stems, veins and tobacco leaf material can be comminuted bymeans of a suitable type of mill, such as a ball mill or colloid mill.Any desired ratio of tobacco material to water can be used. It has beenfound that ratios of 1:8 to 1:14 give satisfactory results. When themilling or slurry-forming operation is completed, the slurry isdeposited in a film-forming device and applied in the form of acontinuous film or web upon a suitable film-forming surfac such thatwhen the slurry is spread out in the form of a film or web thereon,substantially all soluble and insoluble constituents of the tobaccostems and veins will be contained in a reconstituted tobacco sheet orfilm. The tobacco film can be coated with encapsulated clove oilflavoring material while in either wet or dry condition. If desired, ondrying, the resulting web may be shredded.

Alternatively, this invention encompasses the mixing of previouslyshredded tobacco with capsule slurries whereby the individual capsulesadhere to shreds of tobacco.

The present invention provides means for making the aromatic syntheticclove oil substance constantly available in a fresh condition byencasing it in an easily rupturable capsule located in contiguouscontact .with tobacco.

It is neither necessary nor desirable to rupture the capsules containedin a tobacco smoking article since heat from a buming from of tobaccowill rupture the capsules seriatim thereby releasing aromatic materialsuch that (l) the smoke emanating from the tobacco smoking article ishomogeneously flavored with the synthetic clove oil and, if desired,other tobacco flavor enhancers such as 4-hydroxy-4-methyl-5-hexenoicacid, y-lactone described in Canadian Pat. No. 805,934, and (2) a soundaudible to the human ear is given off at the instant of rupture.

One of the features of the instant invention is the saving in volatilesynthetic clove oil material effected by encapsulation. The evanescenceof the volatile materials is greatly inhibited by the intact capsulewall.

This invention includes the application of one or more other sets ofcapsules throughout shredded tobacco capsule mixtures; and alsothroughout the thickness of the reconstituted tobacco sheet or on theoutside of the sheet, and it does not preclude the presence of othermaterial, particulate or other, present in, on the outside of, orotherwise associated with the shredded tobacco mixture or tobacco sheet,to cooperate, or not, with the set of capsules positioned in the sheetby the practice of this invention cumulatively or countervailing, whichproduce a beneficial effect. There may be two or more sets of capsulesin the mixture or sheet being confined or not confined to the surface ofthe tobacco shreds or sheets or spread throughout the thickness of thesheet or discontinuously through the tobacco mixture.

It is contemplated that the capsules need not be of uniform substance,content and size so long as their diameter is in the range of 50-500microns. The capsules may be a mixture as to size and wall material, orof difi'erent content or origin, to serve one or more utilitarianpurposes in behavior, or, if capsules, to have walls of varyingresistance to rupture or fracture, or to be different in any otheraspect of structure or performance (such as resistance to heat) ordifferent in any olfactory sense characteristics-or to contain, inaddition to the synthetic clove oil, chemical reactants, medicines,perfumes absorbents or adsorbentsas between the fractured andunfractured state or in either stateor to be affected by other forms ofenergy in various manners which will be evident to those skilled in theart. Each of the capsules may be self-contained, in that each, uponrupture, releases its volatile content including synthetic clove oil.The particulate liquid may contain either liquid or solid solutematerial dissolved therein, or have such materials dispersed therein inany physical state, and may contain materials which may be subject togrowth, metamorphosis, or degeneration.

To obtain disunifonnity among capsules if such are used, they may bemanufactured in separate batches according to the characteristics of thecapsules as to origin, size, contents, or wall material and structure,and thereafter blended in the desired proportions for introduction intothe paper as a single applied slurry. This is important where more thanone kind of capsule contents (solid or fluid) is to be made use ofeither by rupture of the capsules or by their characteristics in theunruptured state. It is within the province of this invention to providecapsules having different thicknesses of walls or different strength ofwalls, to the end that they may be differentially fractured byvariations in temperature, so that some capsules may be ruptured by onetemperature and the rupture of other capsules will follow in response toapplication of a greater temperature.

In a preferred embodiment, though not limited thereto, a novel system iscapable of limiting the penetration of capsules containing syntheticclove oil into a shredded tobacco mixture or into a reconstitutedtobacco sheet as the sheet is being formed, so that the particles aresubstantially concentrated subsident to either surface of each of theshreds or of the sheet in a firm, well defined stratum of bindermaterial.

The capsules may be applied to shredded tobacco or tobacco sheet in anaqueous slurry containing a solvent-responsive or solvent-activatedadhesive such as a vegetable gum or starch. It is to be understood thatthe use of such adhesive is not necessary to the operation of thisinvention. Etficacious natural adhesives or binders include hydrolyzedstarches (principally tapioca starch), gum arabic, and gum tragacanth.These adhesives or binders are used exclusively in water solution.(While karaya gum is not actually soluble in water, karaya gum particlesabsorb large amounts of water and swell to great size). Certain watersoluble synthetic adhesives or binders such as polyvinyl alcohol, sodiumcellulose glycolate, and methyl cellulose can be used to bind capsulesonto tobacco shreds or in a reconstituted tobacco web.

The capsules preferably should contain an oily, aromatic liquidcomprising about 85 percent by weight, of the encapsulated structure andcontaining synthetic clove oil; and, if desired, other tobacco flavorenhancers. The oily liquid is released by the rupturing of the capsulewall material. The oily liquid may be a mixture of oils or dispersionsof solids in oils containing, inter alia, 01,13 and y caryophyllene;furfural; eugenol; acetyl eugenol; and eugenyl acetate. The oils canalso include furan, methyl furan, l-hexene, cyclopentadiene, benzene,cyclohexane, and other sesquiterpenes having molecular weights in therange of 204 up to 140. The aggregation of capsules can containdisparate substances within each discrete capsule.

Preferably, from about 60 up to 80 percent of the oil is eugenol; withthe remainder of the oil comprising the other aforementionedingredients.

This invention also includes smoking articles containing two disparateencapsulated substances which act synergistically when the capsulescontaining them are ruptured. The relative proportions of solidparticles to capsules may vary according to the effect desired.

The capsule walls can be made of a gelatin-gum arabic complex,gelatin-carrageenan complexes, phased out succinylated gelatins, ethylcellulose, or other material. Any standard method of encapsulation suchas the one set froth in example l may be used to fonn the capsules.

The size of the capsules can range from approximately 50 microns indiameter to approximately 500 microns in diameter, and may be mixed asto size, or even mixed as to content. Capsules spaced in the cigaretteshould not exceed 500 microns in diameter and should not be less than 50microns, since smaller capsules fail to rupture with a report loudenough to be desirable, and larger capsules may separate too easily fromthe wet tobacco and from the smoking article itself.

The weight ratio of dry tobacco to dry capsules may be in the range ofl:0.0l up to 1:008 with the preferred range being from 110.02 up to1:004.

Capsules of the 50 to 500 micron size can be made according to theprocess disclosed in U.S. Pat. No. 2,800,457, which issued on July 23,1957, to Barrett K. Green and Lowell Schleicher. Briefly, that patentdiscloses film-forming polymeric materials of opposite electric chargein aqueous solution which are caused to form a separate liquid dispersedphase (a coacervate) by modifying the conditions of the solution.

The intended oil contents of the capsules containing synthetic clove oilare emulsified in the solution, and the coacervate forms a liquid filmabout the emulsion. The film is made firm and solid, and is thenhardened. The capsules are recovered ready for their use as part of theheat rupturable composition. The oily material of the preferredembodiment (e.g., a solution containing eugenol) may be modified byaddition thereto of the previously mentioned or other materials ofaromatic or therapeutic properties.

The reconstituted sheet which is made for use in this invention, can beused either in the manufacture of cigars, cigarettes or other likesmoking articles.

In the following description, no distinction is made between the typesof tobacco employed.

In making sheet or film material to be expanded and made available foruse in the manufacture of smoking articles, a suitable slurry can beformed from 75 percent stems, which are run through a convenu'onalcomminuting machine in order to reduce the stems to extremely fine sizeafter which they are mixed with water, and percent tobacco scrap leafportions, dust or fines which have also been passed through hecomminuting machine and preferably screened to remove any foreignmaterial such as sand mixed therewith. The mixture of comminuted stemsand leaves is then placed in a ball mill of known design, and ballmilled for a period of time, preferably sufficient to completely hydrateor gelatinize the particles of tobacco being ball milled. The size ofthe ball mill and balls, and speed of rotation, control the amount oftime necessary to reach the desired state of hydration or gelatinizationof the tobacco particles. For instance, it has been found that in a 4-gallon jar ball mill using three-fourths inch nominal size flintpebbles, the ball milling time may approximate from 6 to 16 hours at 50r.p.m. whereas in a 5-quart ball mill using the same size pebbles at 60r.p.m., the minimum time may run as high as 13 hours.

Upon completion of the slurry, it is removed from the ball mill andplaced in a film-forming device and formed into a continuous sheet orweb. The sheet or web material is then ready for the addition ofcapsules in a slurry.

A primary objective of the invention is to provide a reconstitutedtobacco sheet or shreds with limited penetration of liquid-containingcapsules as the particles that, because of their position in the sheetor on the shreds, when ruptured by heat, release the contained volatileclove oil-flavoring liquid. This objective is accomplished by forming asheet of reconstituted tobacco with the capsules embedded in it or byforming a mixture of tobacco shreds to which have been applied capsuleswhich are adhered thereto or embedded therein. The amount of capsulesapplied should be related to the final sheet or shred thickness and theamount of encapsulated liquid necessary or desirable to be provided, andthe average shred width.

In the application of the subject invention to the production of sheetmaterial, the preferred system comprises laying down a wet web oftobacco fibrous material on a supporting member to form an embryonicsheet, and applying to said web minute capsules, the contents of whichcapsules comprise flavoring material.

Following the formation of the sheet of web, it is moved through amoisture removing zone and excess moisture is removed therefrom.

It is within the scope of this invention to add the capsules by anymeans at any point in the tobacco web formation, provided that the webat the time of addition of the capsules is sufficiently wet andpenetrable, either by reason of undrained liquid or because the capsularparticulate material was added as a liquid slurry, to permit fixation onthe tobacco fibers. Furthermore, it is within the scope of thisinvention to add the capsules to the shredded tobacco at any point inthe shredding operation so that the capsules are not ruptured.

Following are examples of systems that produce either a controlledpenetration of capsules within a reconstituted tobacco sheet or web; orproduce a mixture of shredded tobacco and capsules adhered to thetobacco shreds:

EXAMPLE I The following is a description of a preferred embodiment ofthe invention as carried out using a process wherein minute capsuleshaving a diameter in the range of 50 up to 500 microns were added to awet web of reconstituted tobacco (weight ratio of dry web to drycapsules 1:0.04. The capsules and binder materials (weight ratio of drycapsule to dry binder 1:0.1) when placed among the tobacco fibers, wetthem and entangle with them and clothe them, thus in effect securing andbinding the capsules against migration through the sheet, therebyforming a subsident stratum. The majority of binder and associatedcapsules are caught in the sheet. Substantially no capsules migratethrough the sheet. When the wet tobacco web is dried, the binder shrinksby loss of solvent, leaving the dried polymeric binder material, and thecapsules remain in place relatively with respect to sheet thickness. Thesheets containing the capsules are then shredded and used in producingsmoking articles such as cigarettes. Such cigarettes are formed using awrapper, containing a fill of tobacco extending from one end of thewrapper to the other, and intimately admixed with the tobacco, aplurality of microcapsules each comprising an aromatic volatilesynthetic clove oil flavorant The capsules are homogeneously spaced incontiguous relationship with the tobacco such that as the burning frontof the tobacco advances the length of the tobacco article, a concomitantelevation of temperature initiates consecutive rupture of the capsules(1) releasing the volatile synthetic clove oil-containing material whichemanates with smoke from the smoking article into the smokers mouth and(2) yielding a crackling sound audible to the human ear.

Tragacanth gum solution and starch solution were prepared in thefollowing manner: PART A Concentrated Tragacanth Gum Solution (binder)4.5 pounds of dry traganth gum powder was stirred into 50 gallons ofwater, using a suitable mixer. Five minutes after all the powder hadbeen added, the mixer was turned off. The tragacanth gum solution wasallowed to sit for 2 hours, and then the mixer was turned on for 5minutes. Sitting for 2 additional hours, enabled the traganth gum tohydrate. After five minutes, the mixer was turned ofi, and the 55 gallondrum was covered. Just prior to combining the tragacanth gum solutionand the capsular slurry, 50 gallons of tragacanth gum solution wasdiluted with water to 3 percent tragacanth gum on a solids basis.

PART B Starch Solution prepared in the following manner:

Preparation of Synthetic clove Oil A mixture was prepared containing thefollowing ingredients:

Ingredient Percentage aCaryophyllene 2.0 BCaryophyllene 2.07Caryophyllene l0.0 Furfural 0.1 Eugenol 75.0 Eugenyl Acetate 5.0 AcetylEugenols 5.9

PART D Preparation of Capsular Slurry-Encapsulation of Synthetic CloveOil Ten grams of gum arabic were dissolved at room temperature in 220grams of deionized water. The mixture was agitated until the gum arabicwas fully dissolved. ln a separate 240 milliliter Erlenmeyer flask, 10.0grams of modified gelatin was mixed with 220.0 grams of deionized water.The gelatin was allowed to tumefy at room temperature and also thenwarmed in a water bath to about 40 C. With stirring so that the gelatinwas dissolved.

The gelatin solution and the gum arabic solution were poured into abeaker equipped with a stirrer. A flocculence indicating theprecipitation of the gelatin was noted. The temperature of the mixturewas decreased to 35 C. The speed of the stirrer was adjusted so that itwas turning only enough to keep the phases mixed. The pH of the mixturewas 4.50.

Into the beaker containing the mixture of gum arabic and gelatin waspoured I 18.0 grams of synthetic clove oil as prepared in part C. Thespeed of the stirrer was then adjusted to mix the colloids and the oil.The oil separated into droplets. Two drops of octyl alcohol were addedto prevent foaming. The progress of the coacervation was monitored bymeans of microscopic examination.

The temperature of the mixture was lowered to room temperature e.g., 24C. At the higher temperature of 31 C. colloid deposition was observed onthe oil droplets. At 24 C. little colloid could be observed in aqueousportions of the mixture. Deposition had ceased. Stirring was continuedfor 30 minutes, whereupon the reaction mixture was cooled on an ice bathto 4 C. The reaction mixture was maintained at this temperature for 200minutes. (When hardening was desired, 1.0 milliliters of a 25 percentglutaraldehyde in water per gram of gelatin is added.)

The internal phase of the capsules thus formed was approximately 80-90percent of the total weight of the capsules.

The capsules thus produced had diameters in the range of from 50 up to500 microns. They were coated with the binder onto a tobacco sheetmaterial which was shredded and used as a fill in the manufacture of asmoking article.

PART E Variation of the Encapsulation of Synthetic Clove Oil A variationof the encapsulation procedure set forth immediately supra is shownbelow:

The solution of gum arabic was warmed to 38 C., placed in a Waringblender and stirred. The clove oil prepared in part C was addedgradually while the speed of the blender was being increased until thesize of the clove oil droplets was approximately 50-500 microns. Themixture thus formed was poured into a l,000 milliliter beaker containinggelatin, also at 38 C., and was stirred thoroughly. The temperature wasthen allowed to drop to room temperature and then further decreased to atemperature of 4 C. to 10 C. by means of an ice bath.

it is evident that the tobacco film or filaments can be made fromvarious types and combinations of tobacco. For instance, the tobaccosheet material can be made from relatively expensive tobacco such asLatakia in which it is highly desirous to use all waste because of thehigh price thereof. So, also, it may be formed of Burley or one or morescrap or waste cigarette type tobaccos and incorporated in accordancewith a particular cigarette manufactures formula as if it were naturalcigarette tobacco leaves. Any desired formula can thus be maintained inaccordance with the demands of a manufacturer's particular brand usingone or more types of natural shredded tobacco leaves and admixed desiredquantities of shredded capsule containing tobacco film material orfilaments, either as a blending or flavoring medium or both or forpurposes of bulking.

In the case of the manufacture of cigarettes, according to the presentinvention, tobacco films are shredded into strands or the film is formeddirectly into filaments substantially the width of the strands ofnatural shredded tobacco and of any desired length. In the case ofcigars, the capsule containing films are use in large pieces much aslong filler tobacco in forming long fller cigars. In all cases theshredded films or filaments or film used in cigarettes and cigars can behandled either manually or by machine in the same manner as naturalshredded tobacco leaves or whole leaves or portions thereof. The amountof shredded capsule-containing reconstituted tobacco or pieces of thismaterial employed in a particular blend in cigarettes or cigars,respectively, will vary according to types of tobacco used in the sheetmaterial and the requirements of a particular manufacture.

EXAMPLE ll The following is a description of another preferredembodiment of the invention as carried out using a process wherein anaqueous slurry of minute capsules having diameters in the range of50-500 microns were admixed with shredded natural leaf tobacco.

The capsules and binder materials, when placed among the tobacco shreds,wet them and entangle with them thus securing the capsules againstdisengaging from the tobacco shreds and separating from a smokingarticle produced therefrom. Such cigarettes are formed using a wrapper,containing a fill of tobacco extending from one end of the wrapper tothe other, and ultimately admixed with the tobacco, a plurality ofmicrocapsules each comprising an aromatic volatile synthetic clove oilflavorant. The capsules are homogeneously spaced in contiguousrelationship with the tobacco such that as the burning front of thetobacco advances the length of the tobacco article, a concomitantelevation of temperature initiates consecutive rupture of the capsules(1) releasing the volatile synthetic clove oil-containing material whichemanates with smoke from the smoking article into the smoker's mouth and(2) yielding a crackling sound audible to the human ear. PART AEncapsulation of Synthetic Clove Oil 3750 cubic centimeters of syntheticclove oil produced by the procedure of part C of example i and 315 gramsof gelatin in 6,950 cubic centimeters of water was stirred at 200 r.p.m.(six blade axial flow agitator with four evenly spaced battles) untilthe particle size was in the range of 50 microns to 500 microns(45-minute stirring}. A solution of 315 grams of gum arabic in 6,950cubic centimeters of deionized water was then added. The pH of theresulting mixture was adjusted to 4.5 by the addition of a 10 percentsolution of sodium hydroxide in water. The mixture was slowly cooled ona water bath to a temperature of 38 C. 15 l .5 cubic centimeters of a 25percent solution of glutaraldehyde in water was added. 7.7 grams ofsodium benzoate was added. The resulting capsule slurry was stirred for30 minutes and then filtered using a 20 mesh sieve.

The capsules were then suspended in a mixture of 3 parts gum tragacanthand 17 parts water and the resulting suspension was sprayed ontoshredded natural leaf tobacco (us'mg a two fluid pneumatic atomizingnozzle; 114 J .A.U.SS manufactured by the Spraying Systems, lnc.). Theweight ratio of dry capsule to dry shredded tobacco was 0.04:1. Theproduct was used as a fill for cigarettes which, when smoked, released avolatile clove oil flavor and aroma, and yielded a crackling soundaudible to the human ear.

PART B Alternative Procedure for Encapsulation of Clove Oil Slurry thegum arabic solution. The temperature of the mixture was adjusted to 33C. Thereafter, the solution of gelatin was added with rapid stirring.The reaction mixture was cooled to a temperature of 10 C. on an ice bathwhile continuously stirred. The mixture was stirred for one hour at 10C. Thereafter, 5.0 parts by weight of a percent solution ofglutaraldehyde in water was added to the reaction mass.

The reactant mass was stirred at 10 C. for 8 hours. The resultingcapsules had a spherical diameter in the range of from 50 up to 500microns. The capsules thus formed were not dried but were immediatelysprayed onto shredded tobacco. The resulting product was rolled into acigarette. The cigarette when smoked released a volatile clove oilflavor and aroma and also yielded a crackling sound audible to the humanear.

What is claimed is:

l. A smoking article comprising a wrapper, tobacco disposed in saidwrapper, a plurality of minute rigid-walled, heat rupturable capsuleseach comprising an inner liquid phase of volatile flavoring material,the said inner liquid phase being -90 percent of the total weight ofsaid capsules, said capsules having spherical diameters of from 50 up to500 microns, said capsules being in intimate contact with said tobaccosuch that as a burning front of ignited tobacco advances, the capsulesare ruptured consecutively by a concomitant elevation in temperature (1releasing the volatile flavoring material which is entrained in smokeemanating from the smoking article into a smokers mouth; and (2 yieldinga crackling sound, audible to the human ear.

2. The tobacco article of claim 1 wherein the volatile flavoringmaterial is a volatile synthetic clove oil.

3. The tobacco article of claim 1 wherein the heat-rupturable capsulescomprise in the inner phase a volatile synthetic clove oil and,intimately admixed therewith, an additional tobacco flavor enhancer.

4. The tobacco article of claim 1 wherein the weight ratio of drytobacco to dry capsules is from 1:0.02 up to 1:004.

i i i i

1. A smoking article comprising a wrapper, tobacco disposed in saidwrapper, a plurality of minute rigid-walled, heat rupturable capsuleseach comprising an inner liquid phase of volatile flavoring material,the said inner liquid phase being 80-90 percent of the total weight ofsaid capsules, said capsules having spherical diameters of from 50 up to500 microns, said capsules being in intimate contact with said tobaccosuch that as a burning front of ignited tobacco advances, the capsulesare ruptured consecutively by a concomitant elevation in temperature (1) releasing the volatile flavoring material which is entrained in smokeemanating from the smoking article into a smoker''s mouth; and (2 )yielding a crackling sound, audible to the human ear.
 2. The tobaccoarticle of claim 1 wherein the volatile flavoring material is a volatilesynthetic clove oil.
 3. The tobacco article of claim 1 wherein theheat-rupturable capsules comprise in the inner phase a volatilesynthetic clove oil and, intimately admixed therewith, An additionaltobacco flavor enhancer.
 4. The tobacco article of claim 1 wherein theweight ratio of dry tobacco to dry capsules is from 1:0.02 up to 1:0.04.